1. Field of the Invention
The present invention relates to an image recording apparatus which directly controls a flow of charged toner particles and records an image on a recording medium, and more particularly to an image recording apparatus capable of increasing a charged amount of toner particles.
2. Description of Related Art
There has been conventionally proposed an image recording apparatus which generates an electric field between a control electrode having apertures which can pass charged coloring particles (hereinafter referred to as toner particles) and a back electrode, the image recording apparatus recording the image on a recording medium inserted between both electrodes, by directly controlling the charged toner particles. As an example of this kind of image recording apparatus, there has been proposed an image recording apparatus disclosed in U.S. Pat. No. 3,689,935.
It was difficult, however, to control the toner particles directly by the electric field generated between both electrodes in the above image recording apparatus, unless the large quantity of charged toner particles is transported in the vicinity of the control electrode, and unless the toner particles are supplied so as to form a mist of toner particles.
In order to solve this problem, the inventor of the present invention proposed the image recording apparatus specified in Japanese patent application No. 2-10906 which is capable of transporting the large quantity of charged toner particles in the vicinity of a control electrode and supplying the toner particles so as to form a mist of toner particles. The large quantity of charged toner particles was transported in the vicinity of the control electrode by rotation of a brush roller having a brush supporting the large quantity of charged toner particles thereon. A scratch blade was installed in the position where it contacts the brush of the brush roller, so that the brush would contact the scratch blade and be bent by its own elasticity when the brush roller rotated. When the brush roller further rotated, the brush bent further and came off from the scratch blade. Then, the brush returned to an original condition by its own elasticity. At this moment, the toner particles which were supported on the brush separated from the brush. As a result, the toner particles which separated from the brush formed a mist of toner particles and were supplied below the control electrode.
However, in the image recording apparatus thus constructed, the charged amount of the toner particles is very small because the toner particles are only charged triboelectrically. When the charged amount of the toner particles is small, it is difficult to control the modulation of the flow of the toner particles by the electric field generated between the control electrode and the back electrode. Therefore, the conventional image recording apparatus had many problems such as slow image recording speed, and the apparatus became very large and expensive because it needs to drive the control electrode by applying a high voltage and it is difficult to make the control circuit to IC.